1. Field of the Invention
This invention relates to an improvement of the coupling configuration of an optical connector.
2. Description of the Prior Art
For reference, one conventional optical connector is shown in FIGS. 7 and 8, in which FIG. 7 is a perspective view illustrating the state before a receptacle is coupled with a plug provided on the end of an optical fiber cable and FIG. 8 is a sectional view in the plug insertion direction of an important portion of the receptacle and plug being coupled together. In these drawings, reference numeral 1 indicates a receptacle of rectangular prism shape, on one face of which a cylindrical body having a hole 2 serving as a member to be held is provided, with the end portion around the hole 2 of the cylindrical body having a thick stepped portion, thereby forming a plug lock member 3. An optical converting element 4 such as LED is incorporated and secured in the receptacle 1 so that its light emitting spot 5 is located on the center axis of the hole 2. Reference numeral 6 indicates a plug to which an optical fiber cable 9 of round rod shape having a protection coat 8 therearound is attached. This plug 6 has integral therewith an optical fiber holding cylindrical member 10 capable of being fitted precisely in the hole 2 of the receptacle 1, and the point face of this optical fiber holding member 10 has a small circular hole 10a opened there which is closed by the optical fiber cable so that the end face of an optical fiber 7 can be located on the optical axis of the light emitting spot 5. Inside the optical fiber holding member 10 the optical fiber can be incorporated together with its protection coat 8. On the opposite side of the plug 6 to the above there are provided circularly arm-shaped fixing portions 12, 12, . . . with slits left therebetween, and inside these fixing portions 12, 12, . . . the optical fiber cable 9 is press-fitted and secured by caulking a fixing member 11 therearound by means of external pressure. The end portion of the optical fiber cable 9, from which the protection coat 8 is removed a desired length, is fitted in the hole 10a of the optical fiber holding member 10, and the end surface is finished at the outer end face of the optical fiber holding member 10. Around the periphery of the optical fiber holding member 10 of the plug 6 there formed concentrically and integrally therewith elastic lock segments 13, 13, . . . with slits left therebetween, and the end portion each of these lock segments 13, 13, . . . has a projection engagable with the stepped portion of the plug lock member 3. As the holding member 10 is inserted the projections of the lock segments 13, 13, . . . move inward by means of their elastic strength and are engaged with the stepped portion of the plug lock member 3. In the thus attained state, the end face of the optical fiber 7 arranged on the end of the optical fiber holding member 10 is located closely on the optical axis of the light emitting spot 4; thus, an optical signal can be transmitted.
However, according to such a coupling configuration as above of the optical connector, due to external stress applied to the optical fiber cable 9, it comes out of coupling or turns, the positional relationship between the foregoing light emitting spot 4 and the end face of the optical fiber 7 changes, and the optical conversion efficiency varies; thus, the transmission of the optical signal is unstable. To solve the foregoing problem one configuration has been devised which is similar to that used in the air joint, for example, and is characterized in that by sliding a push member in the plug insertion direction it pushes lock segments so that they are secured on a member to be locked. However, this known configuration has the defect that if an adapter is moved through handling in the course of making a network of optical fiber cables under abutment of the push member on the corner of a desk, for example, the push member tends to move in the plug insertion direction so that its locked state will be released.